disk check at boot up time

Steve Morris samorris at netspace.net.au
Sun Feb 5 20:28:45 UTC 2012


Hi,
     Just my 2 cents worth. If you look at /etc/fstab at the entries for 
each device, there are 2 numbers on the end of each entry, as I 
understand things these are related to whether or not an "fsck" is done 
on the associated device, again as I understand things, if these are set 
to 0 then an "fsck" is not performed.
     Also, if the machine is not shutdown cleanly, for example when 
Ubuntu refuses to terminate and you are forced to physically power off 
the shut the machine down (for whatever reason it can't shut down 
normally), the disk is left flagged a "dirty" or is in an "unstable" 
state. The next time you boot, the boot process takes a significant 
amount of time to complete because the system is replaying all the 
journaled transactions from the previous session (this is in the 
situation where you are actually using a journaling file system). I have 
been in the situation where requiring a physical power off to shut the 
machine down has destroyed an ext3 file system.

regards,
Steve


On 06/02/12 06:44, ray burke wrote:
> basil and friends,
>
> thanks for all your help, and yes its better to be safe than sorry, so
> I won't concern
> myself about it!
>
> ray
>
> On 2/5/12, Leslie Anne Chatterton<lahc2007 at gmail.com>  wrote:
>> Basil,
>>
>> There is no "yes or no" answer possible.
>>
>> In a perfect world it wouldn't matter. Unfortunately minor errors in
>> writing to disk will happen. Even though it's extremely rare, compared to
>> the billions of bytes written, even one altered bit can trash a whole file
>> or programme. Fortunately most errors can be corrected if caught quickly
>> before they can start a cascade of consequent errors. That is what fsck is
>> there to do.
>>
>> Now you could probably go for years without getting caught by this kind of
>> disk corruption, but... wouldn't it be nice to have as much free and fast
>> "insurance" as the wit of clever programmers can devise?
>>
>> I thought so. Now you have your answer.
>>
>> Sent from my Motorola Xoom Android tablet
>> On Feb 5, 2012 5:30 AM, "Basil Chupin"<blchupin at iinet.net.au>  wrote:
>>
>>> On 05/02/12 18:19, Jonas Norlander wrote:
>>>
>>>> 2012/2/5 Basil Chupin<blchupin at iinet.net.au>:
>>>>
>>>>> On 05/02/12 07:33, ray burke wrote:
>>>>>
>>>>>> can anyone help?
>>>>>>
>>>>>> I have been told to insert "sudo touch /forcefsck" in a terminal
>>>>>> window when log into
>>>>>> Â k10.10mm so as to force
>>>>>> a disk check at next boot time of which I have done, but every time I
>>>>>> boot up now is does
>>>>>> the fsck, and I only want it to do it once, so what is the command to
>>>>>> do
>>>>>> this?
>>>>>>
>>>>>> ray
>>>>>>
>>>>> "sudo rm /forcefsck" removes the file and should stop the file system
>>>> check at boot unless there is something wrong with your file system so
>>>> its marked dirty.
>>>>
>>>>   Why are you worried about it?
>>>>> A quick fsck is done everytime you boot to make sure that there has been
>>>>> no
>>>>> corruption to your file sysem (assuming here that you have used ext3 or
>>>>> ext4
>>>>> when you installed). And there is a more comprehensive fsck done after
>>>>> every
>>>>> (?)20 boots of the system.
>>>>>
>>>>> BC
>>>>>
>>>> If I understand it right, when using a journaling file system it will
>>>> not be checked unless its marked dirty by the kernel, a check is
>>>> forced by /forcefsck, max-mount-count or interval-between-checks has
>>>> been reach.
>>>>
>>>> You can check the current values max-mount-count and
>>>> interval-between-checks with "sudo tune2fs -l /dev/sda1". Replace sda1
>>>> with your partition to check.
>>>>
>>>> See "man tune2fs" for more info and how to fine tune the file system
>>>> and when a check is forced.
>>>>
>>> Question: does it matter or not if the file sysem is quicly checked on
>>> each boot?
>>>
>>> Yes or No?
>>>
>>> BC
>>>
>>> --
>>> A three-year-old boy was examining his testicles while taking a bath.
>>> "Mum" he asked, "are these my brains?"
>>> "Not yet," she replied.
>>>
>>>
>>>
>>> --
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